The correct option is
B 6.6 cm
⇒ We know that all the sides of the rhombus are equal. We have given side is 6cm and one diagonal is 10cm.
⇒ Draw a line segment PQ = 6cm.
⇒ Take P as a center with radius 10cm and draw an arc.
⇒ Take Q as a center with radius 6cm and draw an arc meeting previous arc at point R.
⇒ Take P as a center with radius 6cm and draw an arc.
⇒ Take R as a center with radius 6cm and draw an arc meeting previous arc at point S.
⇒ Join PR, QR, RS, PS and QS.
⇒ Thus, PQRS is the required rhombus.
⇒ We have to measure length of the other diagonal which is QS.
∴ QS=6.6cm